package com.jiankang.util;
import java.io.ByteArrayOutputStream; 
public class Base64  
{  
	private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',  
		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',  
		'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };  

	private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55,  
		56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,  
		21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,  
		47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };  

	public Base64()  
	{  
	}  

	public static String encode(byte[] data)  
	{  
		StringBuffer sb = new StringBuffer();  
		int len = data.length;  
		int i = 0;  
		int b1, b2, b3;  

		while (i < len)  
		{  
			b1 = data[i++] & 0xff;  
			if (i == len)  
			{  
				sb.append(base64EncodeChars[b1 >>> 2]);  
				sb.append(base64EncodeChars[(b1 & 0x3) << 4]);  
				sb.append("==");  
				break;  
			}  
			b2 = data[i++] & 0xff;  
			if (i == len)  
			{  
				sb.append(base64EncodeChars[b1 >>> 2]);  
				sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
				sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);  
				sb.append("=");  
				break;  
			}  
			b3 = data[i++] & 0xff;  
			sb.append(base64EncodeChars[b1 >>> 2]);  
			sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
			sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);  
			sb.append(base64EncodeChars[b3 & 0x3f]);  
		}  
		return sb.toString();  
	}  

	public static byte[] decode(String str)  
	{  
		byte[] data = str.getBytes();  
		int len = data.length;  
		ByteArrayOutputStream buf = new ByteArrayOutputStream(len);  
		int i = 0;  
		int b1, b2, b3, b4;  

		while (i < len)  
		{  

			/* b1 */  
			do  
			{  
				b1 = base64DecodeChars[data[i++]];  
			}  
			while (i < len && b1 == -1);  
			if (b1 == -1)  
			{  
				break;  
			}  

			/* b2 */  
			do  
			{  
				b2 = base64DecodeChars[data[i++]];  
			}  
			while (i < len && b2 == -1);  
			if (b2 == -1)  
			{  
				break;  
			}  
			buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  

			/* b3 */  
			do  
			{  
				b3 = data[i++];  
				if (b3 == 61)  
				{  
					return buf.toByteArray();  
				}  
				b3 = base64DecodeChars[b3];  
			}  
			while (i < len && b3 == -1);  
			if (b3 == -1)  
			{  
				break;  
			}  
			buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  

			/* b4 */  
			do  
			{  
				b4 = data[i++];  
				if (b4 == 61)  
				{  
					return buf.toByteArray();  
				}  
				b4 = base64DecodeChars[b4];  
			}  
			while (i < len && b4 == -1);  
			if (b4 == -1)  
			{  
				break;  
			}  
			buf.write((int) (((b3 & 0x03) << 6) | b4));  
		}  
		return buf.toByteArray();  
	}  }
